1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device suitable for manufacture of a TFT (Thin Film Transistor) used in, for example, a liquid crystal display or an organic light emitting display, a method of manufacturing a display apparatus, an apparatus of manufacturing a semiconductor device, and a display apparatus.
2. Description of the Related Art
A TFT substrate is used in an active matrix liquid crystal display or an organic light emitting display. The TFT substrate is obtained by forming a semiconductor film which is amorphous or of polycrystal having a relatively small grain diameter on a substrate, performing an annealing operation by irradiating the semiconductor film with a laser beam, and forming a TFT as a drive element. In some cases, the semiconductor film is directly irradiated with a laser beam. There is also a case that a light absorption layer is formed over the semiconductor film and a laser beam is indirectly applied to the semiconductor film from the light absorption layer side.
To realize higher throughput of a laser annealing apparatus, it is desirable to use a linear beam. In particular, a laser diode has high output stability and the cost is low, so that a large-grain-size semiconductor film is formed stably. Therefore, by using the laser diode as the light source of the laser annealing apparatus, a TFT with high mobility and little variations is able to be realized at low cost.
However, in the case of using a laser diode, since the size of a beam spot is very small, scan time per unit area increases, productivity deteriorates, and manufacturing cost increases. Therefore, to realize higher throughput of annealing, a method of making a laser beam reciprocate or a method of disposing a plurality of lasers close to each other in order to irradiate a large area and simultaneously irradiating a plurality of parts in an amorphous semiconductor film with a plurality of laser beams is employed. By the method, the scan time is shortened, and productivity is increased.